Water relations, temperatures, and mineral nutrients in Pedicularis dasyantha (Scrophulariaceae) from Svalbard, Norway

The arctic vascular hemiparasite Pedicularis dasyantha has a lower diffusion resistance for water vapour than any associated species. Excised leaves die within one hour of drought stress under laboratory conditions, in spite of a high succulence. Transpiration rates of P. dasyantha in the field are almost two times higher than in Dryas octopetala , which is the most important host within investigated sites.
Diffusion resistances are higher in inflorescences than in leaves, probably because the dense pubescence reduces transpiration rates and raises temperatures in inflorescences to 14°C above air temperature on clear days.
Pedicularis dasyantha contains significantly more N, P, and especially K than its host. The high rate of transpiration probably enables the hemiparasite to capture a larger fraction of nutrients supplied by the xylem of its host.